Thank you for contacting JustAnswer.
I am sorry to hear that you are having such a difficult situation with your daughter. Family issues with someone who is not behaving responsibly can be quite difficult. It can be especially disturbing when it puts your grandchild at risk.
Given that you are in the home when she goes out, it may not be considered abandonment, unless you specifically notify her that you are unable to watch your grandson. You can certainly check with ChildLine about whether they would consider this abuse. ChildLine can be reached at(NNN) NNN-NNNNor
It is certainly possible that substance abuse may be playing a part in your daughter's actions. Unfortunately, the more you enable her to not have to face the consequences of her actions, the more she will continue these behaviors. It can be very difficult to employ tough love, particularly if you are fearful for your grandson. You may be able to set limits without telling her to move out. However, it can be very difficult to reason with someone who is abusing substances.
You may find Alanon helpful in providing information for family members of those with addictions: http://www.al-anon.alateen.org/
Keep in mind that you can give your daughter unconditional love without enabling or agreeing with her choices. Even more importantly, you can give unconditional love and support to your grandson which will help him to be more resilient throughout his life. I hope this answer is helpful. Please let me know if I can clarify further.